Heartworm extract induces relaxation of isolated rat thoracicaorta

[摘要] Isolated rat thoracic aortic strips undergoing noradrenaline-induced contraction weretreated with an adult heartworm (HW) crude extract and then examined for isometric changesin tension. HW extract caused relaxation of endothelium-intact strips, but notendothelium-denuded strips. This effect was inhibited by treatment withNG-nitro-L-arginine methyl ester hydrochloride (L-NAME)and could be reversed by additional treatment with L-arginine. However, HW extract at ahigh concentration caused slight relaxation of endothelium-denuded strips, and relaxationpersisted after L-NAME treatment in endothelium intact-strips. These data suggested thatthe relaxation induced by HW extract was mainly endothelium-dependent, nitricoxide-mediated, but in part, also endothelium-independent. In addition, a bioassay usingisolated rat thoracic aortas may be a useful tool for investigating vasoactive substancesin the HW extract.

[学科分类] 兽医学

[关键词] Dirofilaria immitis;heartworm extract;rat aorta;relaxation